| In recent years,with the rapid growth of world trade and the environmental pollution,green development has attracted extensive attention of the international community.LNG,with its advantages in price,technology and accessibility,has become the most concerned alternative fuel for ships in the shipping industry at this stage.With people’s understanding of LNG and technological progress,the development of LNG fuel-powered ships has begun over the world.Although the development of LNG power ship in China started late,it has made a series of achievements,mainly concentrated on inland bulk carriers,and its application on passenger ships is still in the tentative stage.With the approaching of IMO’s sulfur emission limitation in 2020,LNG power ships are expected to further develop.However,because LNG power ships are very different from the traditional fuel-driven ships in working principle and other aspects,and is still in the early stage of development,there are some potential safety hazards.Passenger ships are social activities involving more people so risks are particularly sensitive to LNG-powered passenger ships.Therefore,it is very important to understand the risks of LNG power passenger ships and avoid them to the greatest extent.At the same time,the analysis results can provide reference for the design of LNG power passenger ship and further improve the industry specifications.In this paper,Risk analysis on a 380-passenger LNG power river passenger ship during the night tour of the Pearl River is carried out.Based on the theory of formal safety assessment,risk identification and risk analysis are carried out under three conditions: filling process,mooring and navigation.Finally,the risk index design is carried out to provide a solution for the risk evaluation and comparison of different LNG power river passengers ships.The main research works are listed as follows:(1)The theory of safety evaluation is discussed from two aspects of principle and significance,and several commonly used safety evaluation methods are introduced.In this paper,the concept,development and analysis steps of FSA method,and a feasibility analysis on the application of FSA method to LNG power passenger ship risk assessment are summarized.Finally,the consequence model theory of LNG powered passenger ship is introduced from three aspects: leakage,diffusion and fire.(2)The filling mode of Tank truck-to-ship bunkering(TTS)is introduced,and the risk assessment of the filling process of TTS is carried out by the fault tree model.According tothe statistical data and calculation formulas,combined with the actual situation of the target,the accident probability of orifice leakage,mid-orifice leakage and full-orifice leakage is selected.The natural gas diffusion and the thermal radiation consequences of fire were simulated by PHAST software for the Incident-prone scenarios,the possible scenarios and the most likely scenarios.And the personal risk value and its influence range were also calculated.(3)Pressure release system of LNG power passenger ship is introduced.The release amount and rate of BOG were analyzed.Five release scenarios were set up according to the different ambient temperature,atmospheric stability and wind speed.The safe berthing distance of LNG power river passenger ship is calculated by monitoring the BOG concentration range of the observation ship and the thermal radiation range of the heat source ship.Finally,the preventive measures are given for the safety of LNG power river passenger ship berthing.(4)The LNG power passenger ship is introduced from three aspects: fuel system,power system,monitoring and safety system.For LNG power passenger ships,four kinds of risks are identified: power loss,fire,explosion and low temperature damage.Subsequently,the Delphi method is used to identify the engine room fire-explosion risk of LNG power passenger ship during its voyage.The fault tree is established and qualitative analysis shows that there are 864 minimum cut sets and 3 minimum path sets in the engine room fire and explosion accident for LNG power passenger ship.Among them,the structural important factor of "failure to remedy in time" is the largest.Finally,the relevant improvement measures are given according to the analysis results.(5)The concept of risk index is introduced,and the advantages of applying risk index are analyzed according to index theory.On this basis,a comprehensive risk index model of LNG power river passenger ships is constructed,which is analyzed from the working conditions of filling,mooring and sailing.Then the comprehensive risk index of LNG power passenger ship is calculated from two aspects of weight coefficient distribution and factor index evaluation,and the final risk index value is obtained.This value can be used to compare the risks among different ships,and it is convenient for managers to make reasonable choices for safety management of LNG power passenger ships. |
